Shelf life of working solutions?

[zoharzohar]

How long can Diluted dev/stop/fix last (assuming of course it hasn't been exhausted) if it is stored in sealed containers? Also does this stuff really work? Has anyone used it?

 

[Xmas]

It says on the packing.

If you scratch mix it says on the formula.

Rodinal concentrate lasts a century or so if you screw the cap back on.

 

[heterolysis]

Protectan spray should work if it is what it says. I haven't tried it personally, but it uses the same principles that are used when packaging extremely sensitive chemicals. In the chemistry lab, argon is used because it blankets the surface of your solution and minimizes contact with oxygen, as it is more dense. The cheaper route, Nitrogen, is less dense than oxygen/air, but you can bubble it through the solution (parge) and this will blow away not only oxygen at the surface of the solution, but any dissolved gases as well before you put the cap back on. Parging is always a good idea if you want to be sure your solutions are free of unwanted gases.

Find a welding supplier and buy a cylinder of argon. It's much more cost-effective than buying Protectan

 

[Ricardo Miranda]

For Foma chemistry, here is the catalogue with very detailed info: http://www.foma.cz/ew/92cad2bd-ec2b-4442-bc3c-b13be9ea63ff-en

For Ilford chemistry, you'll have to look at the individual datasheets.

 

[Doremus Scudder]

Difficult question to answer since you aren't very specific with your question. Plus, as others have hinted, you should be reading the information published by the manufacturer. Ilford and Kodak have tons of information available and your questions should be answered there. Other companies do so as well.

However, in the interest of helping out:

Developers: Concentrates have different shelf-lives. Some like Rodinal and HC-110 last practically forever. Others, especially powders that you mix with water (e.g., D-76) have shelf-lives measured in weeks. Shelf life is dependent on storage conditions. Read about your particular developer(s).

Most of us use developer working solutions one-shot; therefore, no storage once mixed and used. Another option is a replenishment scheme. Read up on this if you're interested. It is usually only economical and practical for large-volume operations, but many here use Xtol replenished.

Stop bath: Acetic acid indicator stop baths can be saved and used until the indicator starts to change from yellow to blue (don't wait till it has changed completely; toss it at the first sign of color change). Citric acid stop baths (Ilford, et al.) don't like to be stored; they grow bacterial slime. One session use is best for these. If you're using a non-indicator stop, just use it one session and toss it. Stop is cheap.

Fixer is a whole different issue: Read the Ilford sheet on Rapid Fixer here: http://www.ilfordphoto.com/Webfiles/2006130218312091.pdf . The parts about storage and capacity apply roughly to all rapid fixers. Fixer dies from two causes, chemical exhaustion and aerial oxidation. Plus, you don't want to overuse your fixer. I recommend two-bath fixing for important negatives and fiber-base papers. I don't like to save and re-use fixer; I mix enough for a session. If the session is small, I just waste a little. Note: don't use fixer used for film for paper and vice-versa. Proper fixing is worth reading about and understanding well if you're really interested in permanence.

Best,

Doremus